Reed switch



May 10, 1966 G. WINTRlss REED SWITCH Filed Jan. 21, 1964 ATTORNEYS.

3,250,875 REED SWITCH George Wintriss, Carversville, Pa. Filed Jan. 21, 1964, Ser. No. 339,228 Claims. (Cl. 200-87) This invention relates to reed switches and more particularly to an assembly in which the terminals of a reed switch are permanently connected with conductors of an electric cable, and the switch, terminals and conductors are protected in a housing and are part of a unitary and sealed assembly secured to the end of the cable.

It is an object of theinvention to increase the utility of reed switches by providing an inexpensive unitary assembly that includes such a switch having its terminals connected at the factory with conductors of an electric cable and permanently sealed in a housing attached to a fitting on the cable. Installation involves only the connecting of the cable with the circuit in which the switch is to be used, and the securing of the assembly in position, usually by clamping.

' Another object is to provide a reed switch assembly of the character indicated with a reinforced end adapted to be clamped and with the free end of the reed remote from the clamped end so as to leave unobstructed space for relative movement of a magnet with respect to the switch for operating the switch.

Still another object is to provide a compact reed switch assembly with a plurality of conductors extending lengthwise of the outside of the tube and with the conductors located on the same side of the tube, the conductors being insulated and lightly clamped against the tube by a snugly fitting housing that encloses the tube, its terminals, and the conductors.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIGURE l is a side elevation showing a reed switch assembly made in accordance with this invention and clamped in position to have the switch operated by movement of a magnet;

FIGURE 2 is a sectional view through the assembly illustrated in FIGURE 1', the section being taken through -the diameter of the assembly parallel to the axis; and

FIGURES 3 and 4 are sectional views taken on the lines 3-3 and 4-4, respectively, of FIGURE 2.

The assembly includes a housing 10 having a closed upper end 11 and having its lower end closed by a fitting 14. This fitting 14 extends upwardly into the housing 10 and serves as a reinforcementwithin the housing so that the housing can be firmly gripped by a clamp 16 to hold the housing in a fixed, selected position.

In the construction illustrated, `the clamp 16 is pushed against the housing 10 by a clamping screw 18 which screws through a fixed block 420 to force the clamp 16 and the housing 10 against a fixed bracket 22. This construction is merely representative of means for clamping the housing in a fixed position.

Marking on the outside of the housing 10, preferably a circumferential line 24, indicates the upper limit of the fitting 14 and thus informs the user of the invention of the extent to which the housing 10 can be inserted into United States Patent O 3,250,875 Patented May 10, 1966 a clamp without having the clamp Contact with the housing beyond the reinforcing provided by the fitting 14.

The housing 10 encloses a reed switch, which will be described in connection with FIGURE 2, and this reed switch is actuated by magnet 2S which is moved toward and from the housing 10 or in other directions to shift the flux of the magnet in such a way as to actuate the reed switch within the housing. Marking on the upper part of the housing 10, including a circumferential line 30, indicates the level of the contacts in the reed switch and thus informs the user of the switch of the effective locations for the magnet 28 when the flux field of -the magnet is to produce an actuation of the switch.

An electric cable 34vextends from the housing 10 and I through the fitting 14. This cable 34 is preferably insulated and includes a plurality of conductors, here shown as conductors 41, 42 and 43. These conductors are preferably in stranded relation with one another within the cable 34. The fitting 14 grips the cable 34 tightly so that ythere can be no relative movement of the cable 34 with respect to the fitting 14; and the housing 10 is locked against relative movement with respect to the fitting 14 by a bottom edge 46 of the housing extending into va circumferential groove in the fitting 14, as will be more fully described in connection with FIGURE 2. v I

FIGURE 2 shows a reed switch 50 which includes a tube 52, preferably made of glass, sealed at both ends. A reed 54 is connected at its lower end with a lower terminal 56 that extends through the end of the tube 52. The lower terminal 56 is connected to the conductor 41, preferably by welding, and the insulation 41 on the conductor 41 extends beyond the cable 34 and close to the end of the tube 52.

In the upper end of the tube 52 there is a nonferrous contact 58 and a ferrous contact 59. These contacts are spaced from one another and they are held in place by terminals 61 and 62 which extend through the upper end of the tube 52 and which are connected with the contacts 58 and 59, respectively.

The reed 54 extends between the contacts 58 and' 59. In the preferred construction, the reed 54 has a spring bias toward the contact 58 and remains against this contact 58 at all times except when the reed switch is subjected to a magnetic fiux field of sufficient intensity to operate the switch.

T-he reed 54 is made of ferrous material, the term ferrous material being used herein to designate any material which is attracted by the flux field of a magnet. When the magnet 28 is located on the same side of the tube 5 2 as is the contact 59, the magnet pulls the reed S4 away from the contact 58 and up against the contact 59. By having the contact 59 made offerrous material, the reed 54 is attracted to the contact 59 by the flux field 0f a magnet outside the housing 10, even though the magnet is not on the same side of the tube as is the contact 59.

The terminals 6'1 and 62 extend for a short distance beyond the upper end of the tube 52 and they are connected with the conduct-ors 42 and 43, respectively, preferably by welding. In the preferred construction, the conductors 42 and 43 are connected to corresponding sides -of the terminals 61 and 62 and both of the conductors 42 and 43 extend down the outside of the tube 52 on the same .side of the tube, as clearly shown in FIG- URE 3. This requires clearance between the tube 52 and the housing 10 on onlyone side of the assembly and thus makes the assembly more compact. It also has the advantage o-f making the insulation on the conductors 42 and 43 serve as a packing between the tube 52 and the housing 1li, and the housing'is made so as to fit snugly over the assembly and to clamp the insulation of the conductors 42 and 43 lightly against the outside surface of the tube 52.

The housing 1t) is preferably made of metal and it is n important to prevent the upper end 11 fro-m contacting with the terminals 61 and 62 or the conductors 42 and 43. A disc 64 of electrical insulating material is sho-wn located in the upper end of the housing 10. This is a safety precaution and is ordinarily unnecessary because the housing is held, in a manner which will be described, against movement with re-spectto the tube 52, and in a position that leaves the upper end 1.1 spaced from the terminals 6'1 and 62 and the conductors 42 and 43 by a distance gre-at enou-gh to avoid any short-circuiting of the electric circuits by the upper end 11 of the housing.

The fitting 14 is swedged or otherwise tightly clamped on the cable 34 so that it has no relative movement with respect to the cable 34. There is a circumferential groove 70 in the outside surface of the fitting 14. VThis groove has side walls which maybe curved or straight, the preferred construction being a curved contour, as shown in FIGURE 2. The bottom edge 46 of the housin-g 10 is distorted after the housing is brought into the desired position on the fitting 14,-Y so that this lower edge extends into the groove 4f) and into contact with both the uppery and lower Wall of the groove so that the groove holds the housing 10 against axial movement in both directions on the fitting i4.

The reed switch 50 is held in a definite position with respect to the cable 34 by the connections of the terminals of the reed switch with the conductors 41-43 of the cable. Since the fitting 14 is held against movement with respect to the cable, and since the housing 1lb is locked against movement on the fitting 14 by the groove 70, it will be evident that the housing 10 is also held in a definite and fixed relation to the cable 34 and the reed,l

switch 50. Y j

The construction illustrated has the important advantage, however, that it provides f-or wide manufacturing tolerances. By having the reed switches 50 'supported above the fitting 14 by its connections to the conductors 411-43, and by having clearance between the top of the housing 10 and the upper end of the reed switch 50, the assembly is not affected by manufacturing tolerances in the length of reed switches or variations in the connections of the terminals of the reed switch with the conductors 41H43 of the cable 34. When the assembly is completed, however, the reed switch and all of its connections are completely enclosed in an assembly which is sealed by the extension of the bottom edge 46 into the groove'70; and the entire assembly is firmly secured to end of the cable 3'4 so that connection of the reed switch v into a circuit merely requires the connecting of the cable" conductors 41-43 in the circuit; and replacement is easily effected if a switch ever becomes defective.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications Vcan be made and some features can be used in different less than the diameter of the electric cable and being deformable under outside clam-ping pressure, ra reinforcing fitting within the shell and in contact with the inside surface thereof, and bracing the shell against deforming under such outside clamping pressure, the reinforcing fitting surrounding the cable and being tight thereon, and the shell having fastening means connecting it with the reinforcing fitting so as to connect the shell with the cable, the connection of the shell to the cable being at one end of the shell beyond the end of the tube, said tube being supported by the conductors and the shell, and said shell being a unitary s-tructure with the electric cable, some of the terminals being at different ends of the tube, different conductors connecting with the different terminals and at least one of the conductors extending lengthwise of the tube between the tube and the shell, the shell bein-g closed at its upper end remote from the electric cable, and said electric cable extending through the lower end of the shell. l

2. The reed switch assembly described in claim 1 characterized by two conductors from the upper end of the tube with insulation thereon and held against the outside of the tube by the housing'and contacting with the tube along parallel lines on the same side of the tube and spaced fro-m one another around the circumference of the tube and holding the tube against the side of the housing on the side opposite said two conductors whereby the insulated conductors and the side of the housing prov-ide three angularly spaced supports restraining the Vtube against transverse displacement.

6. The reed` swit'chrassembly described in claim 2 characterized by the conductors that are connected to Ithe terminals at the upper end of the tube being welded to s-aid terminals, and oneof the elements of the welded connections being adjacent to the closed end of the tube but retained out of contact therewith.

4. The reed switch assembly described in claim 2 characterized by three conductors coming together in the insulation jacket cable before passing through the reinforcing fitting, and the fitting being firmly'secured to the cable to prevent longitudinalmovement of the cable with respect to the fitting, the tube being held in a definite relation to the fitting by its connection to said conductors.

l5. The rreed switch assembly described in claim 4 characterized by the reinforcing fitting having a circumferential groove therein, and the end of the housing shell extending over the fitting and snugly gripping the fitting, a portion of the housing shell extending into the groove and locking the housing on the fitting and constituting the fastening means connecting the shell with said reinforcing fitting. Y

I6. rlhe reed switch assembly described in claim 5 characterized by there being walls on opposite sides of the groove, and the edge portion of the shell being the part of the housing that extends into the groove and said edge portion of the shell extending into contact with both of Ysaid Walls of the groove so as to lock the housing against axial movement with respect to the fitting in both directions.

7. yThe reed switch assembly described in claim 1 characterized by the reinforcing fitting extending from the lower end of the housing and for a substantial disstance up into the housing, and the housing having marking on the out-side thereof indicating the upper limit of the fitting within the housing and the resulting upper limit of the area of the housing that can be safely clamped by pressure against the outside of the housing.

8. The reed switch assembly described in claim 7 characterized by adjustable clamping means firmly gripping t'he housing below said marking and leaving the lupper portion of the housing unobstructed for movement of a magnet toward and away from the outside of the housing at the region of the contacts that are within the tube.

9. The reed switch assembly described Aiin claim 1 References Cited by the Examiner characterized by the outside of the housing having mark- UNITED STATES PATENTS ang thereon 1nd1cat1n g the level of the housing at which lthe contacts in the tube are looated, Iand a magnet mov- 2,071,384 2/1937 Barrett 20m-90 able toward and from the region of said marking to ac- 5 2,264,746 12/1941 Euwood 20o-87 mate the reed 2,459,306 1/ 1949 `Burton 200-87 l tact which is non-ferrous, and the other contact being y a ferrous contact and capable of attracting the reed when 10 BERNARD A' GILHEANY P' "nary Examine' in a flux eld of the magnet. J. J. BAKER, Assistant Examiner. 

1. A REED SWITCH ASSEMBLY INCLUDING AN ELECTRIC CABLE CONTAINING A PLURALITY OF CONDUCTORS ENCLOSED IN AN INSULATING JACKET, A REED SWITCH COMPRISING A TUBE WITH CONTACTS THEREIN AND TERMINALS EXTENDING FROM THE CONTACTS THROUGH THE WALL OF THE TUBE, THE TERMINALS BEING CONNECTED WITH DIFFERENT ONES OF THE CONDUCTORS, AND A SHELL PROVIDING A HOUSING OVER THE TUBE, THE SHELL ENCLOSING A SINGLE CHAMBER WITH A WALL THICKNESS SUBSTANTIALLY LESS THAN THE DIAMETER OF THE ELECTRIC CABLE AND BEING DEFORMABLE UNDER OUTSIDE CLAMPING PRESSURE, A REINFORCING FITTING WITHIN THE SHELL AND IN CONTACT WITH THE INSIDE SURFACE THEREOF, AND BRACING THE SHELL AGAINST DEFORMING UNDER SUCH OUTSIDE CLAMPING PRESSURE, THE REINFORCING FITTING SURROUNDING THE CABLE AND BEING TIGHT THEREON, AND THE SHELL HAVING FASTENING MEANS CONNECTING IT WITH THE REINFORCING FITTING SO AS TO CONNECT THE SHELL WITH THE CABLE, THE CONNECTION OF THE SHELL TO THE CABLE BEING AT ONE END OF THE SHELL BEYOND THE END OF THE TUBE, SAID TUBE BEING SUPPORTED BY THE CONDUCTORS AND THE SHELL, AND SAID SHELL BEING A UNITARY STRUCTURE WITH THE ELECTRIC CABLE, SOME OF THE TERMINALS BEING AT DIFFERENT ENDS OF THE TUBE, DIFFERENT CONDUCTORS CONNECTING WITH THE DIFFERENT TERMINALS AND AT LEAST ONE OF THE CONDUCTORS EXTENDING LENGTHWISE OF THE TUBE BETWEEN THE TUBE AND THE SHELL, THE SHELL BEING CLOSED AT ITS UPPER END REMOTE FROM THE ELECTRIC CABLE, AND SAID ELECTRIC CABLE EXTENDING THROUGH THE LOWER END OF THE SHELL. 